Ion formation in an inhomogeneous corona discharge

Abstract

The energy deficit of laser assisted field-evaporated ions from the surface of a non-metallic nano-metric tip is reported as a function of the laser power and ion current. A new model is proposed to explain these results and a good agreement between the theoretical predictions and the experimental results is obtained.In this paper, the mechanism(s) of ion formation in an inhomogeneous electric field produced by a pointed electrode is discussed. At atmospheric pressure, the corona discharge arises under potential difference of ca. 3 kV at a 2 mm distance between a plane and this electrode with a radius of curvature of 0.1 mm. In spite of rather simple experimental realization and a great number of the results previously obtained, the physical processes underlying the corona discharge at these experimental conditions are not totally understood. Our conclusions and findings are in order.1) By means of the induced polarization, the polarized molecules are adsorbed on the surface of a pointed electrode.2) The adsorbed molecules form surface monolayer, and every molecular dipole is affected by the surface of adsorbent, by the Coulomb influence of an external electric field and by lateral exchange-type interaction of the neighboring molecules. It is assumed that the hyperpolarization takes place, i.e. the adsorbed dipoles turn into the Rydberg states. The trajectories of outer shell electrons acquire the characteristics of the Keplerian motion with apocenter and pericenter, where the velocity of electrons differ each from other. 3) The ionization potential of dipoles is decreased due to their Rydberg states, and ionized dipoles are emitted from the surface of an adsorbent. 4) The emitted dipoles are undergone the relaxation of the dipole moment accomplishing by the dipole radiation over a broad band (from 250 nm to 800 nm). 5) The UV radiation with photon energy in the range from 1.5 eV to 6 eV gives a rise of the surface ionization current of adsorbed molecules and it is sufficient of their desorption as well. 6) The Trichelli pulses could be explained via these phenomena. 7) The proposed model is confirmed by the experimental results obtained by mass spectrometric and spectroscopic studies on the discharge radiation.The mechanism of ion formation in an inhomogeneous electric field produced by a pointed electrode is discussed. The hyperpolarization of adsorbed molecules due to their lateral interaction on the surface of an emitter is proved. It is shown that the UV dipole radiation of the emitted ionized molecules stimulates the secondary ionization processes of adsorbent and neutral molecular species of environmental. The proposed mechanism is confirmed by the mass spectrometric and spectroscopic studies on the discharge radiation.